Not a jelly

Jellyfish seem like pretty simple creatures, and they are, relatively. In my zoology class in high school, I remember learning about them not long after sea sponges, which are the most basic organisms. Specifically, I wanted to focus this post on the Portuguese Man-of-war. I thought that it was a jellyfish, but brief research shows that it isn't actually a jellyfish, it's a siphonophore, which means that it's a colonial organism - it's composed of individuals called zooids. The zooids are highly specialized, and dependent on each other.

The name, man-of-war, comes from the fact that the creature floats on the surface of the ocean because a large portion of it is filled with air, so it looks like a ship. It has no means of propulsion, so it's moved by tides and winds and just floats along the surface. The man of war can deflate its pneumatophore in order to briefly submerge underwater if need be. The long stinging tentacles are darkly colored blue and purple and are used to sting and kill small fish and shrimp. Detached tentacles and dead specimens washed up on beaches can sting just as painfully as the live organisms and can remain potent for hours or days after separation from the other parts. The stings are painful and very unpleasant; I have firsthand experience.

This is interesting; the blanket octopus carries around broken man of war tentacles for defense and offense. That would be a cool avenue of research. I wondered what ate the man of war, and apparently it's a regular part of the loggerhead turtle diet. There's a sea slug and a snail that both also consume the Portuguese man of war.

All of this information was courtesy of Wikipedia: Portuegese Man of War.